Iran has resumed 20% uranium enrichment at an underground nuclear facility, the government said on Monday, breaching a 2015 nuclear pact with major powers and possibly complicating efforts by US President-elect Joe Biden to rejoin the deal.
The move is the latest Iranian contravention of the deal, which it started violating in 2019 in response to Washington's withdrawal from the agreement in 2018 and the reimposition of US sanctions that had been lifted under the accord.
"A few minutes ago, the process of producing 20% enriched uranium has started in Fordow enrichment complex," government spokesman Ali Rabeie told Iranian state media.
The step was one of many mentioned in a law passed by Iran's parliament last month in response to the killing of the country's top nuclear scientist, which Tehran has blamed on Israel. Such moves by Iran could hinder attempts by the incoming Biden administration to rejoin the deal.
The deal's main aim was to extend the time Iran would need to produce enough fissile material for a nuclear bomb, if it chose to, to at least a year from roughly two to three months. It also lifted international sanctions against Tehran.
On Jan 1, the International Atomic Energy Agency said Tehran had told the watchdog it planned to resume enrichment up to 20% at Fordow site, which is buried inside a mountain.
"The process of gas injection to centrifuges has started a few hours ago and the first product of uranium hexafluoride (UF6) gas will be available in a few hours," Rabeie said.
"The process has started after taking measures like informing the UN nuclear watchdog."
Iran had earlier breached the deal's 3.67% limit on the purity to which it can enrich uranium, but it had only gone up to 4.5% so far, well short of the 20% level and of the 90% that is weapons-grade.
US intelligence agencies and the IAEA believe Iran had a secret, coordinated nuclear weapons programme that it halted in 2003. Iran denies ever having had one.